Magnetic Nanostructures with Perpendicular Anisotropy for Room Temperature Skyrmions

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Non-Technical Abstract:Magnetic skyrmions are a special type of arrangements of magnetic moments following a particular winding configuration. They possess some fascinating properties. For example, they cannot be continuously deformed to a state where all the moments point to the same direction. Skyrmion magnetic configurations are stable once they are formed, but a key challenge has been the realization of magnetic skyrmions at ambient conditions. This project focuses on construction of artificial skyrmion arrays, operational at elevated temperatures. The physical properties of these skyrmions are studied using a set of experimental techniques as well as simulations. These artificial skyrmions are expected to be stable even at room temperature and in zero magnetic field, thus are an exciting novel platform to explore the intriguing skyrmion physics. They also may have potential applications in highly energy-efficient data storage, magnetic memory and logic devices. This project provides opportunities to train junior researchers in university as well as national laboratory and user facilities. The principal investigator plans to initiate and actively participate in a variety of efforts to broaden participation from underrepresented groups through course offering, internships, exchange visits with partner universities, and other specific programs at the Magnetism Conference.Technical Abstract:Room temperature artificial skyrmion lattices based on nanostructures with perpendicular anisotropy are realized over macroscopic areas. A multi-step nanofabrication process is employed to achieve a variety of artificial magnetic skyrmions, including embedded skyrmion lattices, skyrmion "race-tracks", and skyrmion lattices on curved substrates. A set of magnetic field sequences is followed to establish the skyrmion states. Microstructural characterizations, magnetometry, first-order reversal curve, magnetic imaging, polarized neutron reflectometry, and magneto-transport measurements are carried out to probe the spatial and magnetic profile of skyrmions, their topological characteristics, stability, mobility, and dynamic responses to external stimuli. Simulations are employed to provide insight and guidance to the experiments. These studies not only help to advance fundamental understanding of artificial magnetic skyrmions, but also have potentially important technological impacts in low dissipation information storage, magnetic memory and logic devices, due to the topologically protected quantum states of the skyrmions. They also offer potentials to transform the energy landscape for future nanoelectronics in the "beyond Moore's law" era, which is well aligned with the National Strategic Computing Initiative and the Big Data Initiative, as well as grand challenges for future nanoelectronics. The principal investigator plans to initiate and actively participate in a wide variety of efforts to broaden participation from the international community, students, female scientists and other underrepresented groups, through his extensive service to the magnetism community. Students involved in the project receive excellent exposure to research experience in university, national laboratory and other research facilities.